The majority of personal computing and communication devices are now powered by batteries, and therefore require a battery charger (which may sometimes also provide operating power when the device is stationary). Common examples are notebook computers and cell phones. If the user is traveling, he or she must carry a separate charger for each device, which can be cumbersome. Wireless chargers, such as those based on induction techniques, can reduce the amount of cabling each charger requires, but do nothing to reduce the number of chargers the user needs to carry or store.